1. Combine first 9 ingredients in a blender or food processor; process until smooth. Combine nut mixture and chicken in a large bowl; cover and refrigerate 3 hours or overnight.
2. Heat a large Dutch oven over medium-low heat. Coat pan with cooking spray. Add onion, cardamom, and cinnamon stick to pan; cover and cook 10 minutes or until onion is golden, stirring often.
3. Add chicken mixture to pan; cook 10 minutes, stirring frequently. Stir in broth, tomato puree, paprika, and salt, scraping pan to loosen browned bits. Cook 1 hour or until thick. Stir in half-and-half; cook 1 minute, stirring occasionally. Remove from heat. Discard cinnamon stick. Garnish with fresh cilantro, if desired.